Aircraft propellers

ABSTRACT

An aircraft propeller taper bore insert apparatus is provided. The apparatus includes a tapered outer surface and an inner surface. The outer surface is dimensioned and configured to fit within and be of substantially a same size and shape as an aircraft propeller taper bore or an aircraft propeller balancing tube. The inner surface defines an inner cavity configured to receive a balancing medium and includes a plurality of retention formations arranged thereon and configured to support the balancing medium.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation and claims benefit of thefiling date of U.S. patent application Ser. No. 13/208,897 filed on Aug.12, 2011 and of the same title, which application is incorporated hereinby reference.

BACKGROUND OF INVENTION

This invention is generally related to propeller systems, and moreparticularly, example embodiments of the present invention are relatedto systems for balancing aircraft propellers.

Propeller systems typically include a hub to which two or more propellerblades are coupled. Rotation of the hub causes the blades to rotate. Inorder for the rotation to be smooth the blades are typically balanced.

BRIEF DESCRIPTION OF INVENTION

According to an example embodiment of the present invention, an aircraftpropeller taper bore insert apparatus includes a tapered outer surfaceand an inner surface. The outer surface is dimensioned and configured tofit within and be of substantially a same size and shape as an aircraftpropeller taper bore or an aircraft propeller balancing tube. The innersurface defines an inner cavity configured to receive a balancing mediumand includes a plurality of retention formations arranged thereon andconfigured to support the balancing medium.

According to another example embodiment of the present invention, apropeller blade includes a propeller body defining a taper bore cavity,a balancing tube arranged within the taper bore cavity, and a taper boreinsert. The taper bore insert includes an outer surface and an innersurface. The outer surface is dimensioned and configured to fit withinthe balancing tube, the inner surface defines an inner cavity configuredto receive a balancing medium, the inner surface comprises a pluralityof retention formations arranged thereon, and the plurality of retentionformations are configured to support the balancing medium.

According to yet another example embodiment of the present invention, anaircraft propeller system includes a propeller hub, a first aircraftpropeller blade arranged on the propeller hub, and a second aircraftpropeller blade arranged on the propeller hub opposing the firstaircraft propeller blade. The first aircraft propeller blade and thesecond aircraft propeller blade each include a propeller body defining ataper bore cavity, a balancing tube arranged within the taper borecavity, and a taper bore insert. Each taper bore insert includes anouter surface and an inner surface. Each outer surface is dimensionedand configured to fit within the balancing tube, the inner surfacedefines an inner cavity configured to receive a balancing medium, theinner surface comprises a plurality of retention formations arrangedthereon, and the plurality of retention formations are configured tosupport the balancing medium.

BRIEF DESCRIPTION OF EACH FIGURE OF DRAWING OF INVENTION

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a diagram of an aircraft propeller taper bore insert,according to an example embodiment;

FIG. 2 is a diagram of an aircraft propeller taper bore insert thatincludes a balancing medium disposed therein, according to an exampleembodiment;

FIG. 3 is a diagram of an aircraft propeller blade, according to anexample embodiment;

FIG. 4 is a diagram of an aircraft propeller blade, according to anotherexample embodiment; and

FIG. 5 is a diagram of an aircraft propeller system, according to anexample embodiment.

DETAILED DESCRIPTION OF INVENTION

Conventionally, to achieve proper balance moments in propellers used inaircraft, lead wool is positioned within a hollow core of a taper boreportion of propellers. It should be appreciated that lead is generallyconsidered environmentally unfriendly and thus aircraft propellersystems using lead wool may prove difficult to properly service and/ordispose of.

Example embodiments of the present invention provide novel aircraftpropeller taper bore balancing systems which can negate or reduce theneed for lead wool to achieve proper balance of the blades. A technicaleffect of one embodiment includes the use a variety of differentmaterials according to a particular availability of material withoutresorting to the use of environmentally unfriendly materials to balancea propeller system.

Turning to FIG. 1, an aircraft propeller taper bore insert isillustrated. The taper bore may be an interior portion of an aircraftpropeller's blade. As illustrated, the taper bore insert 100 includes anouter surface 101 and an inner surface 102. As illustrated, the outersurface 101 may be shaped and dimensioned to be of substantially thesame size and shape as a conventional propeller taper bore. That is, thetaper bore insert 100 can be configured such that it may be positionedwithin a taper bore within a propeller blade. The inner surface 102defines an inner cavity 103. Furthermore, the inner surface 102 mayinclude a plurality of retention formations 104 arranged thereon.

As shown, the retention formations 104 may protrude inwardly from theinner surface 102 into the inner cavity 103. The retention formations104 may extend along the entire inner surface 102 forming “ribs,” or maybe segmented or finger-like protrusions. Alternatively, the retentionformations 104 may be grooves or groove-like indentation formationsformed in the inner surface 102. Also, the retention formations 104 mayinclude discontinuous indentations (e.g., dimple-like features)comparable to the discontinuous protrusions noted above, orcomplimentary to the linear features noted for both protrusions andindentations (i.e., ribs and grooves).

According to example embodiments, the retention formations 104 provide amechanical support arrangement for allowing adhesion of a fillermaterial thereto such that a balancing medium may be dispersed andsupported within the inner cavity 103. For example, such is illustratedin FIG. 2.

As illustrated in FIG. 2, balancing medium 202 comprises a plurality ofparticles 201. For example, particles 201 may be formed of any suitablematerial allowing for proper balancing of an aircraft propeller, forexample, steel shot, copper shot, steel pellets, copper pellets, sand,ceramic pellets, rocks, or any other suitable material. Each particlemay be of relatively the same size or may be of different sizes.

The balancing medium 202 further comprises a filler material 203 fillingthe expanses between particles. The filler material 203 may be a binderor matrix allowing for adhesion to the discreet particles 201 and innercavity of the taper bore insert, or simply a mechanical interference fitbetween the balancing medium and the taper bore insert, and may includean adhesive, thermoplastic, elastomer, thermoset polymeric resin, gel,sealant, wax or any other suitable material configured to restrictmovement of the particles 201 within the inner cavity 103. Although notparticularly illustrated, it should be understood that the taper boreinsert 100 may be sealed or unsealed depending upon any desiredimplementation. For example, a sealing plug, cap, or insert may bearranged to compress and seal the balancing medium 202. Further, asealing plug or plug-like member, cap, threaded sealing member, orinsert may be positioned to seal the entire inner cavity 103.

Therefore, according to example embodiments, an aircraft propeller taperbore insert may be filled with a balancing medium 202 to achieve aproper balance moment of an aircraft propeller. Hereinafter, additionalexample embodiments more clearly illustrating installation of taper boreinserts within aircraft propellers are provided with reference to FIGS.3-5.

Turning to FIG. 3, a portion of an aircraft propeller blade isillustrated. The aircraft propeller blade 300 includes a propeller body301 and a support body 302. The propeller blade 300 further includes asupport medium 320 (e.g., cushion or foam) arranged within the supportbody 302 proximate the propeller body 301. The support body 302 includespitch control formation 321 disposed to allow modification of a pitch ofthe propeller body 301.

As further illustrated, the propeller body 301 includes a taper boresurface 304 defined in a cavity 303. The cavity 303 may be filled with acushioning material or may be relatively empty. Furthermore, the cavity303 may be solid, for example, formed of any suitable lightweightcomposite material, or metals such as aluminum, titanium, or anysuitable metal alloy. The taper bore surface 304 further defines aninternal taper bore cavity including balancing tube 305 arrangedtherein. The balancing tube 305 may be formed of any suitable material,including lightweight composite materials and/or metals such asaluminum, titanium, or any suitable metal alloy. The balancing tube 305defines cavity 350 configured to receive a taper bore insert.

As further illustrated, the propeller blade 300 includes the taper boreinsert 306 arranged within the cavity 350. The taper bore insert 306includes an outer surface 361 and an inner surface 362. As illustrated,the outer surface 361 may be shaped and dimensioned to be ofsubstantially the same size and shape the cavity 350. The inner surface362 may define inner cavity 363. Furthermore, the inner surface 362 mayinclude a plurality of retention formations 364 arranged thereon.

As shown, the retention formations 364 may protrude within the innercavity 363. The retention formations 364 may extend along the entireinner surface 362 forming “ribs,” or may be segmented or finger-likeprotrusions. Alternatively, the retention formations 364 may be groovesor groove-like indentation formations formed in the inner surface 362.Also, the retention formations 364 may include discontinuousindentations (e.g., dimple-like features) comparable to thediscontinuous protrusions noted above, or complimentary to the linearfeatures noted for both protrusions and indentations (i.e., ribs andgrooves).

According to example embodiments, the retention formations 364 provide amechanical support arrangement for allowing adhesion and support ofbalancing medium 372 comprising filler material 373 and particles 371therein. The balancing medium 372 may be substantially similar to thebalancing medium 202 described above.

Thus, as described above, example embodiments provide aircraftpropellers comprising a propeller body, a support body, and a taper borecavity disposed within the propeller body. The taper bore cavity mayinclude a balancing tube arranged therein. Further, the balancing tubemay define a cavity configured to receive a taper bore insert. The taperbore insert may be substantially similar to the insert 100 illustratedin FIGS. 1-2 and the insert 306 of FIG. 3. However, according to someexample embodiments, a taper bore insert may be omitted, and a balancingtube may be formed and configured to retain a balancing medium therein.

For example, turning to FIG. 4, a portion of an aircraft propeller bladeis illustrated. The aircraft propeller blade 400 includes a propellerbody 401 and a support body 402. The propeller blade 400 furtherincludes a support medium 420 (e.g., cushion or foam) arranged withinthe support body 402 proximate the propeller body 401. The support body402 includes pitch control formation 421 disposed to allow modificationof a pitch of the propeller body 401.

As further illustrated, the propeller body 401 includes a taper boresurface 404 defined in cavity 403. The cavity 403 may be filled with acushioning material or may be relatively empty. The taper bore surface404 further defines an internal taper bore cavity including balancingtube 405 arranged therein. The balancing tube 405 may be formed of anysuitable material, including lightweight composite materials and/ormetals such as aluminum, titanium, or any suitable metal alloy.

As further illustrated, the balancing tube includes an outer surface 451and an inner surface 452. As illustrated, the outer surface 451 may beshaped and dimensioned to be of substantially the same size and shapethe inner cavity 450. The inner surface 452 may define inner cavity 450.Furthermore, the inner surface 452 may include a plurality of retentionformations 454 arranged thereon.

As shown, the retention formations 454 may protrude within the innercavity 450. The retention formations 454 may extend along the entireinner surface 452 forming “ribs,” or may be segmented or finger-likeprotrusions. Alternatively, the retention formations 454 may be groovesor groove-like indentation formations formed into the inner surface 452.Also, the retention formations 454 may include discontinuousindentations (e.g., dimple-like features) comparable to thediscontinuous protrusions noted above, or complimentary to the linearfeatures noted for both protrusions and indentations (i.e., ribs andgrooves).

According to example embodiments, the retention formations 454 provide amechanical support arrangement for allowing adhesion and support ofbalancing medium 472 comprising filler material 473 and particles 471therein. The balancing medium 472 may be substantially similar to thebalancing medium 202 and 372 described above.

Thus, as described above, example embodiments provide aircraftpropellers comprising a propeller body, a support body, and a taper borecavity disposed within the propeller body. The taper bore cavity mayinclude a balancing tube arranged therein. Further, the balancing tubemay include an inner surface having a plurality of retention formationsarranged thereon configured to support a balancing medium within thebalancing tube. Thus, proper balance moment of a propeller may beachieved.

Turning now to FIG. 5, an aircraft propeller system is illustrated. Asshown, the system 500 includes a first propeller blade 501 and a secondpropeller blade 502 supported by propeller hub 513. The first propellerblade 501 and the second propeller 502 may be substantially similar topropeller blades 300 or 400. For example, the first propeller blade 501may include a taper bore cavity 511 defined therein, and configured toreceive the balancing tube 305 and taper bore insert 306; oralternatively, the balancing tube 405. Furthermore, the second propellerblade 502 may include a taper bore cavity 512 defined therein, andconfigured to receive the balancing tube 305 and taper bore insert 306;or alternatively, the balancing tube 405. Thus, the system 500 may bebalanced using any of the balancing mediums described herein, and maytherefore avoid the use of lead wood as in conventional systems.

Alternatively, the first propeller blade 501 and the second propellerblade 502 may include any conventional propeller including a taper boreinsert cavity or any suitable cavity configured to receive the taperbore insert 100.

Furthermore, although particularly illustrated as including twopropeller blades, it should be readily understood that exampleembodiments may include propeller systems with any desired number ofpropeller blades.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. An aircraft propeller taper bore insert apparatus comprising: atapered outer surface that is dimensioned and configured to fit withinand be of substantially a same size and shape as an aircraft propellertaper bore or an aircraft propeller balancing tube; and an inner surfacethat defines an inner cavity configured to receive a balancing mediumand includes a plurality of retention formations arranged thereon andconfigured to support the balancing medium.
 2. The apparatus of claim 1,wherein the balancing medium is arranged within the inner cavity andincludes a filler material and balancing material.
 3. The apparatus ofclaim 2, wherein the filler material is a binder, adhesive, elastomer,gel, sealant, or wax.
 4. The apparatus of claim 2, wherein the balancingmaterial is at least one of metal shot, metal pellets, ceramic shot,ceramic pellets, rocks, and sand.
 5. The apparatus of claim 1, whereinthe retention formations are ribs formed on the inner surface.
 6. Theapparatus of claim 1, wherein the retention formations are protrusionsformed on the inner surface.
 7. The apparatus of claim 1, wherein theretention formations are grooves formed in the inner surface.
 8. Apropeller blade comprising: a propeller body defining a taper boresurface that, in turn, defines a taper bore cavity; a balancing tubethat is arranged within the taper bore cavity and defines a balancingtube cavity; and a taper bore insert that is configured to be receivedin the balancing tube cavity and includes: a tapered outer surface thatis dimensioned and configured to fit within and be of substantially asame size and shape as the balancing tube cavity; and an inner surfacethat defines an inner cavity configured to receive a balancing mediumand includes a plurality of retention formations arranged thereon andconfigured to support the balancing medium.
 9. The propeller blade ofclaim 8, wherein the balancing medium is arranged within the innercavity and includes a filler material and balancing material.
 10. Thepropeller blade of claim 9, wherein the filler material is a binder,adhesive, elastomer, gel, sealant, or wax.
 11. The propeller blade ofclaim 9, wherein the balancing material is at least one of metal shot,metal pellets, ceramic shot, ceramic pellets, rocks, and sand.
 12. Thepropeller blade of claim 8, wherein the propeller blade comprisesfurther a support body that is proximate the propeller body and includesa pitch change portion configured to change a pitch of the propellerbody.
 13. The propeller blade of claim 8, wherein the balancing tube isformed of aluminum, titanium, an alloy of titanium, or an alloy ofaluminum.
 14. The propeller blade of claim 8, wherein the plurality ofretention formations are a plurality of ribs formed on the innersurface.
 15. The propeller blade of claim 8, wherein the retentionformations protrusions formed on the inner surface.
 16. The propellerblade of claim 8, wherein the retention formations are grooves formed inthe inner surface.
 17. An aircraft propeller system comprising: apropeller hub; a first aircraft propeller blade that is arranged on thepropeller hub; and a second aircraft propeller blade that is arranged onthe propeller hub, wherein each of the first and second aircraftpropeller blades includes: a propeller body defining a taper boresurface that, in turn, defines a taper bore cavity; a balancing tubethat is arranged within the taper bore cavity and defines a balancingtube cavity; and a taper bore insert that is configured to be receivedin the balancing tube cavity and includes: a tapered outer surface thatis dimensioned and configured to fit within and be of substantially asame size and shape as the balancing tube cavity; and an inner surfacethat defines an inner cavity configured to receive a balancing mediumand includes a plurality of retention formations arranged thereon andconfigured to support the balancing medium.
 18. The system of claim 17,wherein the first and second aircraft propeller blades include furtherthe balancing medium arranged within respective inner cavities and thebalancing medium includes a filler material and balancing material. 19.The system of claim 18, wherein the filler material is an adhesive,elastomer, gel, sealant, or wax.
 20. The system of claim 18, wherein thebalancing material is at least one of metal shot, metal pellets, ceramicshot, ceramic pellets, rocks, and sand.